The mercury cell problem and its solutions. Index. Page 1: Index and general information on mercury battery problems and solutions. 2: Detailed information on mercury, zinc-air, alkaline, rechargeable and lithium cells. 3: Information on silver-oxide cells, a battery comparison chart and options for replacing 625-mercury cells. 4: Battery adapters and various diodes for use in a camera, exposure meter or adapter. 5: Temperature influence on Schottky-diodes and PX27 battery problem and solutions. 6: Materials and tools needed for making a battery adapter and disclaimer. 7: Elaborate step-by-step guide for making a homemade PX13 / PX625 / MR9 battery adapter. 8: Last piece of the step-by-step guide for making a homemade battery adapter and a list of movie cameras and photo (still) cameras, exposure meters and accessories that use PX13 / PX625 / MR9 cells. 9: List of cameras, exposure meters and accessories that use PX13 / PX625 / MR9 cells. 10: For the more technically challenged: a step-by-step guide for making a battery adapter with tiny S.M.D. parts. 11: Ordering information and prices (incl. shipping costs) for ready-made adapters, kits or a hardcopy of this article. 12-14: F.A.Q. frequently asked questions: please READ this first before you place your order or ask questions. General information about mercury cells and various solutions for replacing the banned mercury cells. The now (for environmental reasons) banned mercury Most batteries that were available in mercury versions cells have caused problems for a lot of (vintage) camera are currently available in silver-oxide and/or alkaline and exposure meter owners who are now facing versions. Lithium cells are not suitable for use in most inaccurate exposures. The constant output voltage (1.35 cameras/exposure meters that were dependant on volts) of the mercury cell was used as a reference mercury cells even when camera manufacturers advise voltage and for powering the meter and surrounding them (see bottom page 2 and 5). Adapters are available electronics. Depending on the circuits in an exposure from various suppliers but usually at high prices (around meter a constant voltage is actually necessary or not. A $ 33.-) beware of unusually high shipping costs that most Pentax Spotmatic, for instance, has a ‘bridge’ measuring suppliers charge. Take shipping costs into account when network and does not need an exact 1.35 volts. This ordering batteries and/or adapters on the web. Check out camera works perfect on a 1.55 volts alkaline or 1.6 volts the following sites for adapters: www.criscam.com and silver-oxide cell. When an alkaline or silver-oxide cell is http://www.smallbattery.company.org.uk/sbc_mercury_ca used instead of a mercury cell without an adapter or other talogue.htm replace PX32, TR164, HM-4N or (2) 640A special measures, deviations of up to 4 Light Values! mercury cells go to the site from the ‘Yashica guy’: (Konica TC) can occur. In general a camera or exposure http://www.yashica-guy.com/document/battery.html they meter will not be damaged when a silver-oxide or alkaline sell adapters for a nice price (around $ 15.-) and with cell is used instead of a mercury cell, however, I cannot ‘normal’ shipping costs. The ‘Yashica Guy Pro Adapter’ guarantee this will be the case for every camera. To replaces the PX32 and equivalents that are used in the check whether or not a camera or exposure meter works Yashica rangefinder camera series: Electro 35 G / GS / correctly on an alkaline cell; measure the exposure on a GT / GSN / GTN / MG-1. For the Lynx 5000E and Lynx bright sky and in a dim lit room with a fresh alkaline cell 14E models there is a replacement for the 2 pieces of and again with a mercury cell or compare the readings 640A mercury cells. There are adapters that cost a few with an exposure meter or camera that exposes correctly. dollars, www.paulbg.com/Nikon_F_meter_batteries.htm If the readings are the same with both cells/exposure these metal rings are intended for physically adapting meters in bright and dim conditions the mercury cell can zinc-air 675-cells so they will fit in a 625-battery be replaced with an alkaline cell without any problems. compartment but do not lower the voltage. These rings There are cameras that do work well on Alkaline cells ! cannot be used with alkaline or silver-oxide cells. If the exposure readings in dim and/or bright conditions Expensive adapters (up to $ 35.00) adapt the common are more than 0.5 L.V. ‘off’ an alternative power source SR44/S76/357 (or 386) silver-oxide cell in size and lower will be necessary once the mercury cell is depleted. For the voltage to 1.35 volts. Another option is to make your slides a variation in exposures of 0.3 L.V. can already be own adapter. On pages 6 to 8 is a comprehensive do-it- a problem. If the camera or exposure meter does not yourself guide for making a homemade adapter like the work properly on alkaline or silver-oxide cells there are a one the right or order this adapter ready-made few options: (see page 11). In the following pages there is more detailed information regarding mercury - Have the camera or exposure meter adjusted to work cells and their replacements and concerns correctly on silver-oxide cells. mainly the PX625 and the PX27 (page 5 ). - Modify the camera/exposure meter by soldering one (or more) Schottky diode(s) in series with the wire from the battery compartment so it can take silver- Dimensions in this article are given in millimetres (mm). oxide cells. (option 5, page 3) To convert millimetres to inches multiply the millimetres - Use zinc-air cells, see page 2. by 0.04 this will give a reasonable approximation. For an - Use one or more ready-made or homemade battery exact conversion: adapter(s). 1 Inch = 25.4 mm, 1 mil (0.001 Inch) = 0.0254 mm. Author: F. de Gruijter, Waddinxveen, The Netherlands. [email protected] version 8.92 - Feb 2013 1 Mercury cells such as PX13, PX14, PX27, PX32, PX400, Stack solution 2: Use a conductive spacer between the PX625, PX640, PX675 and other types are (because of cells with a small piece cut out of it as shown environmental reasons) no longer available, produced on the right. Make this from copper or other and imported in most countries all over the world. The metal foil. The example on the right is made mercury in the cell is a highly toxic heavy metal and can from a conductive self-adhesive foil that can do a lot of damage to the environment. There are many easily be applied to a zinc-air cell as shown manufacturers that made the 625-cell under their own on the left. The glue on this sticker is part number: 4370, 4371, PX13, V13PX, EPX13, conductive. When this sticker is applied to a V625PX, PX625, KX625, RPX625, EPX625, HD625, cell so that one air hole remains open the PN625 RM625, 4625, 625, H1560, H-D, HS-D, M01, sticker will seal off the other holes and MR9, 1124MP, M20 and 8930. Many salesmen do not therefore will last longer. The air can reach the cell know the difference between mercury and alkaline cells through the gap formed by the cut-out part of the sticker. and will try to sell you (in all ignorance) alkaline cells When 675-cells are used to replace PX625 cells you stating these cells are the same as mercury cells and are might need to fill up the space (0.04" = 1 mm per cell) interchangeable without any problems, sadly however, with metal no. 10 flat washer(s) (hardware store). Centre this is not true! There are rumours mercury cells are still the cell with rubber O-rings or, even better, (needed for produced and available in China, look for those on the electrical contact) order the tightly fitting metal ring from web. Make sure you are not sold ‘old stock’ that has been www.paulbg.com/Nikon_F_meter_batteries.htm. waiting on a shelf for 6 years or longer, these cells will For cameras like the Rollei 35’s these solutions are not a certainly not last long! The main reason mercury cells good option because the (half full?) film must be taken were used is the constant output voltage of these cells out of the camera to change the batteries. during their lifespan. This constant output voltage makes simple and effective exposure meter circuits possible There are ‘replacements’ for the PX625, the ‘Wein’ without the need of (expensive) reference components MRB625 and ‘Rittz’ MX625. Regrettably these cells are and a lot of electronics. Their large capacity and low expensive compared to 675-hearing aid cells. These cells prices also made it popular. are 675-cell sized and come with metal adapter-rings to centre them. Both of these cells have fewer holes than Zinc-air cells are intended for use in hearing aids to ‘normal’ 675-cells and, therefore, will last longer. replace mercury cells. The cheap 675-hearing aid cells Unfortunately these metal rings are quite loose around are sold in blisters and can be used in most cameras/ the cell and not easy to apply (not so with the metal ring exposure meters directly but their lifespan is limited to mentioned above). The ‘Wein’ MRB625 also has a only 2 to 4 months depending on make, humidity and somewhat lower output voltage (1.36 volts). It has only 2 temperature whether current is drawn or not since they holes instead of the usual 3 or more; this causes the cell literally dry-out over time.